N-substituted - 8,13-dioxodinaphtho (2,1-b; 2&#39;,3&#39;-d)-furan - 6 - carboxamides as electrically photosensitive materials in electrophotographic processes



June 3, 1969 WEINBERGER 3,448,028

NSUBSTITUTED-8 Iii-DIOXODINAPHTHO (2 l-b; 2 ,3 -d -FURAN-6- CARBOXAMIDES AS ELECTRICALLY PHOTOSENSITIVE MATERIALS IN ELECTROPHOTOGRAPHIC PROCESSES Filed Dec. 28, 1964 INVENTOR LESTER wcmagacsa 6% A T TORNE VS United States Patent York Filed Dec. 28, 1964, Ser. No. 421,280 Int. Cl. B41111 5/20; C23b 13/00; G03g 7/00 US. Cl. 204-181 18 Claims ABSTRACT OF THE DISCLOSURE N-substituted 8,13 dioxodinaphtho (2,1-b; 2',3-d)- furan-6-carboxamides are used as the electrically photosensitive material in photoelectrophoretic, xerographic, and deformation imaging systems.

This invention relates in general to new compositions of matter and methods of using them. More specifically, the invention concerns the use of new electrically photosensitive pigments in electrophotographic imaging systems.

There has been recently developed an electrophoretic imaging system capable of producing color images which utilizes photoconductive pigment particles. This process is described in detail and claimed in copending applications Ser. Nos. 384,737, now US. Patent 3,384,565; 384,681 abandoned in favor of continuation-impart application Ser. No. 655,023 now US. Patent 3,384,566; and 384,680 abandoned in favor of continuation-in-part application 518,041 now US. Patent 3,383,993 all filed July 23, 1964. In such an imaging system, variously colored light absorbing particles are suspended in a non-conductive liquid carrier. The suspension is placed between electrodes, subjected to a potential difference and exposed to an image. As these steps are completed, selective particle migration takes place in image configuration, providing a visible image at one or both of the electrodes. An essential component of the system is the suspended particles which must be intensely colored pigments which are photosensitive and which apparently undergo a net change in charge polarity upon exposure to activating radiation, through interaction with one of the electrodes. The images are produced in color because mixtures of two or more differently colored pigments which are each sensitive only to light of a specific wavelength or narrow range of wavelengths are used. Pigments used in this system must have both intense pure colors and be highly photosensitive. The pigments of the prior art often lack the purity and brilliance of color, the high degree of photosensitivity, and/ or the preferred correlation between the peak spectral response and peak photosensitivity, necessary for use in such a system.

Another imaging system which utilizes electrically photosensitive material is the xerographic process originally described in US. Patent 2,297,691 to C. F. Carlson. Here, the photosensitive material must be an effective photoconductive insulator, i.e. must be capable of holding an electrostatic charge in the dark and dissipating the 3,448,028 Patented June 3, 1969 iCC charge to a conductive substrate when exposed to light. In the fundamental process, a base sheet of relatively low electrical resistance such as metal, paper, etc., having a photoconductive insulating surface coated thereon, is electrostatically charged in the dark. The charged coating is then exposed to a light image. The charges leak olf rapidly to the base sheet in proportion to the intensity of light to which any given area is exposed the charge being substantially retained in non-exposed area, forming a latent electrostatic image. After exposure, the coating is contacted with electrostatic marking particles in the dark. These particles adhere to the areas where the electrostatic charge remains, forming a powder image corresponding to the electrostatic image. Where the base sheet is relatively inexpensive, such as paper, the image may be fixed directly to the plate as by heat or solvent fusing. Alternatively, the powder image may be transferred to a sheet of material, such as paper, and fixed thereon.

Many photosensitive materials useful in the xerographic process are known in the art, e.g., vitreous selenium, sulfur, anthrace'ne, zinc oxide, and polyvinyl carbazole. While several of these different materials are in commercial use today, each has deficiencies in such areas as photographic speed, spectral response, durability, reuseability and cost such that there is a continuing need for improved materials.

A third class of electrophotographic imaging which utilizes electrically photosensitive materials has recently been developed. This class consists of two systems of surface deformation imaging which are generally referred to as frost imaging and relief imaging. Frost imaging is described in detail in a publication entitled A Cyclic Xerographic Method Based on Frost Deformation by R. W. Gundlach and C. I. Claus, Journal of Photographic Science and Engineering, January-February edition, 1963. Relief imaging is described in detail in US. Patents 3,055,006; 3,163,872; and 3,113,179.

For use in frost imaging, for example, a plate may be made by overcoating a conductive substrate with a layer of a photoconductive insulating material, which is then overcoated with a thermoplastic material. Alternatively, the photoconductive material may be dispersed in particulate form in the thermoplastic layer and the mixture coated directly over the conductive substrate. Typically, a uniform electrostatic charge is imposed on the plate surface, then the plate is exposed to a light and shadow image to be reproduced. The charge is dissipated in light struck areas but remains in unexposed areas. The plate is heated or treated with a solvent vapor until the electro static attraction forces of the charge pattern exceed the surface tension forces of the film. When this threshold condition is reached, a series of very small folds or wrinkles are spontaneously formed on the film surface, the depth of the wrinkles in any particular area of the film being dependent upon the intensity of charge in that area. This gives the image a frosted appearance. Other methods of frost and relief charging, exposing, and developing are described in the above mentioned publication and patents. Many of the presently known photoconductive materials have an excessively limited spectral response and low photographic speed and, thus, are incapable of reproducing optimum frost or relief images.

-It is, therefore, an object of this invention to provide novel compositions for electrophotographic imaging processes which overcome the above noted deficiencies.

It is another object of this invention to provide novel photosensitive materials suitable for use in electrophotographic imaging processes.

It is another object of this invention to provide novel photosensitive compositions useful in electrophoretic imaging processes.

It is another object of this invention to provide novel compositions having an intense yellow color.

It is yet another object of this invention to provide a novel method of making a new yellow pigment.

It is another object of this invention to provide novel electrophoretic imaging processes.

-It is another object of this invention to provide novel xerographic imaging processes.

It is still another object of this invention to provide novel surface deformation imaging processes.

It is still another object of this invention to provide novel electrophoretic imaging systems capable of reproducing color images.

It is still another object of this invention to provide novel frost imaging processes.

It is still another object of this invention to provide novel frost imaging processes.

It is still another object of this invention to provide xerographic plates having maximum spectral and photosensitive responses in ranges other than those of prior plates.

The foregoing objects and others are accomplished in accordance with this invention, fundamentally, by providing novel compositions having the general formula:

wherein:

W, X, Y, and Z are each selected from the group consisting of O, N, S, Se, and C, at least one of which is other than C;

R is selected from the group consisting of H, CH C H N OCH OC H CN, SO NH SO NHC H CO CH CO C H C1, F, Br, I, and mixtures thereof; and

n is a positive integer from 1-3.

The compositions of the general formula given above belong to the class of N-substituted-8,13-dioxodinaphtho- (2,1-b; 2,3-d)-furan-6-carboxamids, wherein the substituent basically comprises a five membered heterocyclic wherein:

W, X, Y, and Z are each selected from the group consisting of O, N, S, Se, and C, at least one substituent being other than C;

R is selected from the group consisting of H, CH C H N0 OCH OC H CN, SO NH CO CH 00 0 11 SO NHC H C1, F, Br, I and mixtures thereof; and

n is a positive integer from 1-3.

The compositions of this invention have the common characteristics of a brilliant, intense, yellow color; of insolubility in water and common organic solvents, e.g., benzene, toluene, acetone, carbon tetrachloride, chloroform, alcohols, and aliphatic hydrocarbons; and of unusually high photosensitive response.

Of the compositions within the general formula above, N 2"(1",3"thiazole)-8,13-dioxodinaphtho (2,l-b; 2',3- d)-furan-6-carboxamide is preferred for use in electrophoretic imaging processes since it is simply and economically synthesized, has especially pure color, and is most highly photosensitive. This has been found to give the most desirable combination of color and photosensitivity. However, since the shade or the tone of the composition and the spectral and photosensitive responses vary slightly depending upon the substituent used, intermediate values of these variables may be obtained by mixing several of the compositions of this invention.

The following examples further define and describe methods of making the compositions of the present invention. Parts and percentages are by weight unless otherwise indicated. The examples below should be considered to illustrate various preferred embodiments of the invention.

EXAMPLE I About 11.5 parts of 2,3-dichloro-1,4-naphthoquinone is refluxed for about 15 minutes with about 13 parts of N-3' (1',2',4'triazole)-2-hydroxy-3-naphthamide in about 400 parts boiling pyridine. The solution is filtered while warm. The product is washed with pyridine and acetone, then is recrystallized from methyl naphthalene, yielding about 2.8 parts of N-3"(1",2",4"triazole) 8,13 dioxodinaphtho- (2,1-b; 2',3-d)-furan-6-carboxamide having a melting point of about 405 C.

EXAMPLE H About 11.5 parts of 2,3-dichloro-1,4-naphthoquinone is refluxed for about 3 hours with about 13.5 parts of N-2' (1,3thiazole)-2-hydroxy 3 naphthamide in about 100 parts boiling pyridine. The solution is cooled to room temperature and the product is removed by filtration. The product is recrystallized from dimethyl formamide, yielding about 4.5 parts N-2(1",3thiazole)-8,13-dioxodinaphtha-(2,1-b; 2,3-d) -furan-6-carboxamide having a melting point of about 357 C.

In the table below, further examples are given for producing additional embodiments of the compositions of this invention. The table gives the number of the example in column 1, the parts by weight and name of the second reactant in column 2, and the parts by weight and name of the product in column 3. The processes used in preparing the compounds listed in the table are similar to that described in detail in Examples I and II above. In each example, about 22.5 parts of 2,3-dichlor'o-1,4-naphthoquinone is used as the first reactant.

In the chemical formulas as listed in the table below, X in column 2 represents the 2-hydroxy-3-naphthoylportion and Y incolumn 3 represents the 8,1'3-di0xodinaphtho-(2,l-b; 2',3'-d)-furan-6-carbox portion. Thus, for example, X-4-ethoxyanilide represents 2-hydroxy-3-naphthoyl-4'-ethoxyanilide; Y 4" ethoxyanilide represents 8,13-dioxodinaphtho-(2,1-b; 2,3-d)-furan-6-carbox 4"- ethoxyanilide; etc.

N-2 (3 su1fonamidethiophene)-X The compositions within the general formula listed above, and mixtures thereof, are especially useful as photosensitive pigment particles in electrophoretic imaging processes. An exemplary electrophoretic imaging system is shown in the figure.

Referring now to the figure, there is seen a transparent electrode generally designated 1 which, in this exemplary instance, is made up of a layer of optically transparent glass 2 overcoated with a thin optically transparent layer 3 of tin oxide, commercially available under the name NESA glass. This electrode shall hereafter be referred to as the injecting electrode. Coated on the surface of injecting electrode 1 is a thin layer 4 of finely divided photosensitive particles dispensed in an insulating liquid carrier. The term photosensitive, for the purposes of this application, refers to the properties of a particle which, once attracted to the injecting electrode, will migrate away from it under the influence of an applied electric field when it is exposed to actinic electromagnetic radiation. For a detailed theoretical'explanation of the apparent mechanism of operation of the invention, see the above mentioned copending applications, Ser. Nos. 384,737, 384,681 and 384,680, the disclosures of which are incorporated herein by reference. Liquid suspensions 4 may also contain a sensitizer and/ or a binder for the pigment particles which is at least partially soluble in the suspending or carrier liquid as will be explained in greater detail hereinafter. Adjacent to the liquid suspension 4 is a second electrode 5, hereinafter called the blocking electrode, which is connected to one side of the potential source 6 through a switch 7. The opposite side of potential source 6 is connected to the injecting electrode 1 so that when switch 7 is closed, an electric field is applied across the liquid suspension 4 between electrodes 1 and 5. An image projector made up of a light source 8, a transparency 9, and a lens 10 is provided to expose the dispersion 4 to a light image of the original transparency 9 to be reproduced. Electrode 5 is made in the form of a roller having a conductive central core 11 connected to the potential source 6. The core is covered with a layer of a blocking electrode material 12, which may be baryta paper, or other suitable material. The pigment suspension is exposed to the image to be reproduced while potential is applied across the blocking and injecting electrodes by closing switch 7. Roller 5 is caused to roll across the top surface of injecting electrode 1 with switch 7 closed during the period of image exposure. This light exposure causes exposed pigment particles originally attracted to electrode 1 to migrate through the liquid and adhere to the surface of the blocking electrode, leaving behind a pigment image on the injecting electrode surface which is a duplicate of the original transparency 9. After exposure, the relatively volatile carrier liquid evaporates ofl, leaving behind the pigment image. This pigment image may then be fixed in place as, for example, by placing a lamination over its top surface or by a dissolved binder material in the carrier liquid such as parafiin wax or other suitable binder that comes out of solution as the carrier liquid evaporates. About 3 to 6% by weight of parafiin binder in the carrier has been found to produce good results. The carrier liquid itself may be paraffin wax or other suitable binder. In the alternative, the pigment image remaining on the injecting electrode may be transferred to another surface and fixed thereon. As explained in greater detail below, this system can produce either monochromatic or polychromatic images depending upon the type and numbeen produced with voltages ranging from 300 to 5,000

volts, in the apparatus of the figure.

In a monochromatic system, particles of a single color are dispersed in the carrier liquid and exposed to a blackand-white image. A single color image results, corresponding to conventional black-and-white' photography. In' a polychromatic system, the particles are selected so that those of different colors respond to different wavelengths in the visible spectrum corresponding to their principal absorption bands. Also, the pigments should be selected so that their spectral response curves do not have substantial overlay, thus allowing for good color separation and substractive multicolor image formation. In a typical multicolor system, the particle dispersion should include cyan colored particles sensitive mainly to red light, magenta colored particles sensitive mainly to green light and yellow colored particles sensitive mainly to blue light. When mixed together in a carrier liquid, these particles produce a black appearing liquid. When one or more of the particles are caused to migrate from base electrode. 11 toward an upper electrode, they leave behind particles which produce a color equivalent to the color of the impinging light. Thus, for example, red light exposure causes the cyan colored pigment to migrate thereby leaving behind the magenta and yellow pigments which combine to produce red in the final image. In the same manner, blue and green colors are reproduced by removal of yellow and magenta respectively. When white light impinges upon the mix, all pigments migrate leaving behind the color of the white or transparent substrate. No exposure leaves behind all pigments which combine to produce a black image. This is an ideal technique of substrative color imaging in that the particles are not only each composed of a single component but, in addition, they perform the dual functions of final image colorant and photosensitive medium.

It has been found that the compounds of the general formula given above are surprisingly effective when used in either a single or multicolor electrophoretic imaging system. Their good spectral response and high photosensitivity result in dense, brilliant images. It is known that in general cyan and magenta pigment particles separate from the tri-mix more easily and form more dense images than do particles of the usual yellow pigments. The yellow pigments herein disclosed, however, have surprisingly good color separation and image density characteristics.

Any suitable different colored photosensitive pigment particles having the desired spectral responses may be used with the yellow pigments of this invention to form a pigment mix in a carrier liquid for color imaging. From about 2 to about 10 percent pigment by weight have been found to produce good results. The addition of small amounts (generally ranging from 0.5 to 5 mole percent) of electron donors or acceptors to the suspensions may impart significant increases in system photosensitivity.

The following examples further specifically define the present invention with respect to the use of the compositions of the general formula given above in electrophoretic imaging processes. Parts and percentages are by Weight unless otherwise indicated. The examples below are intended to illustrate various preferred embodiments of the electrophoretic imaging process of the present invention. I

All of the following Examples LVIII-LXVI are carried out in an apparatus of the general type illustrated in the figure with the imaging mix 4 coated on a NESA glass substrate through which exposure is made. The NESA glass surface is connected in series with a switch, a potential source, .and the conductive center of a roller having a coating of baryta paper on its surface. The roller is approximately 2 /2 inches in diameter and is moved across the plate surface at about 1.45 centimeters per second. The plate employed is roughly 3 inches square and is. exposed with a light intensity of 8,000 foot candles as measured on the uncoated NESA glass surface. Unless otherwise indicated, 7 percent by Weight of the indicated pigments in each example are suspended in Sohio Odorless Solvent 3440 and the magnitude of the applied potential is 2500 volts. All. pigments which have a relatively large particle size as received commercially or as made are ground in a ball mill for 48 hours to reduce their size to provide a more stable dispersion which improves the resolution of the; final images. In Examples LVIILX, the exposure is made with a 3200 K. lamp through a 0.30 neutral densitystep wedge filter to .measure the sensitivity of the suspensions to white light and then Wratten filters 2 9, 61, and 47b are individually superimposed over the light source in separate tests to measure the sensitivity of the suspensions to red, green, and blue light, respectively.

EXAMPLE LVIII About 7 parts of N-2"(1",3"-thiazole)-8,13-dioxodinaphtho-(2 ,l-b; 2',3-d-furan-6-carboxamide is suspended in about parts Sohio Odorless Solvent 3440. The mixture is coated on a NESA glass substrate and a negative potential is imposed on the roller electrode. The plate is exposed through a Wratten 29 filter and the neutral density step wedge filter, thus exposing the plate to red light. The pigment is found to be completely insensitive to the red light. The above steps are then repeated utilizing Wratten 61, Wratten 47b and no fiter to test for sensitivity to green, blue, and white light, respectively. The pigment is insensitive to green light but equally sensitive to blue and white lights. When exposed to blue or white light, the suspension has good photographic speed and yields images of good density.

EXAMPLE LIX A series of tests is run as in Example LVIII above, except that the pigment here is N-3thiophene-,l3 dioxodinaphtho-(2,1-b; 2',3'-d) -furan-6-carboxamide. Again the suspension is found to be equally sensitive to blue and white light and insensitive to green and red light. The suspension has satisfactory photographic speed and image density.

EXAMPLE LX A series of tests is run as in Example LVIII above, except that the pigment comprises N-2"-furan-.8,13-dioxodinaphtho-(2,1-b; 2',3'-d) -fur an-6-carboxamide. Again the suspension is found to be equally sensitive to white and blue light, but insensitive to green and red light. Good photographic speed and good image density are observed.

In each of the following examples, a suspension including equal amounts of three different colored pigments is made up by dispersing the pigments in finely divided form in Sohio Odorless Solvent 3440 so that the pigments constitute about 8% of the mixture. This mixture may be referred to as a tri-mix. The mixtures are individually tested by coating them on a NESA glass substrate and exposing them as in Example LVIII above, except that a multicolor Kodachrome transparency is interposed between the light source and the plate instead of the neutral density and Wratten filters. ,Thus, a multi-colored image is projected on the plate as the roller moves across the surface of the coated NESA glass substrate. A baryta paper blocking electrode is employed and the roller is held at a negative potential of about 2500 volts with respect to the substrate. The roller is passed over the substrate six times, being cleaned after each pass. Potential application and exposure are both continued during the entire period of the six passes by the roller. After completion of the six passes, the quality of the image left on the substrate is evaluated as to density and color separation.

EXAMPLE LXI The pigment mix consists of, as a magenta pigment, Watchung Red B, a barium salt of l-(4'-methyl-5'-chloroazobenzene 2-su1fonic acid)-2-hydroxy-3-naphthoic acid, C.I. No. 15865, available from Du Pont, as a cyan pigment, Monolite Fast Blue GS, the alpha form of metal free phthalocyanine, C.I. No. 74100, available from the Arnold Hoffman Company, and as a yellow pigment N-3"(l",2,4"-triazole) 8,13 dioxodinaphtho (2,1-b; 2,3-d)-furan-6-carboxamide. This tri-mix, when exposed to a multicolored image, produces a full color image with excellent density and color separation.

EXAMPLE LXII The pigment mixture consists of, as a magenta pigment, Locarno Red X-1686, 01. No. 15865, 1-(4'-methyl-5'- chloroazobenzene 2' sulfonic acid) 2 hydroxy 3- naphthoic acid, available from American Cyanamide, as a cyan pigment, Cyan Blue GTNF, the beta form of cop per phthalocyanine, 0.1. No. 74160, available from Collway Colors, and as a yellow pigment, N-2"(l",3-thiazole) 8,13 dioxodinaphtho (2,1 b; 2,3' d) furan- 6-carboxamide. This tri-mix is exposed to a multicolored image and produces a full color image of excellent density and color separation.

EXAMPLE LXIII The pigment mixture consists of a magenta pigment, Naphtho Red B, l-(2'-methoxy-5'-nitrophenylazo)-2-hydroxy-3"-nitro-3-naphthanilide, C.I. No. 12355, available from Collway Colors; a cyan pigment, a polychloro substituted copper phthalocyanine, C.I. No. 74260 available from Imperial Color and Chemical Company, and a yellow pigment N 2" selenophene 8,13 dioxodinaphtho-(2,1-b; 2',3'-d)-furan-6-carboxamide. This tri-mix is exposed to a multicolored image and produces a full color image of good density and color separation.

EXAMPLE LXIV The pigment mixture consists of a magenta pigment, Vulcan Fast Red BBE Toner 35-2201, 3,3'-dimethoxy- 4,4 biphenyl bis(l" phenyl 3 methyl 4" azo- 2-perylene-5-one), C.I. No. 21200, available from Collway Colors; a cyan pigment, Cyan Blue, 3,3'-methoxy- 4,4 diphenyl bis(1" azo 2" hydroxy 3" naphthanilide), C.I. No. 21180, available from Harmon Colors, and as a yellow pigment N-3"-thiophene-8,13-dioxodinaphtho-(2,1-b; 2,3-d)-furan-6-carboxamide. This tri-mix is exposed to a multicolored image and produces a full color image of good density and color separation.

EMMPLE LXV The pigment suspension consists of a magenta pigment, Indofast Brilliant Scarlet Toner, 3, 4, 9, -bis(N,N'-pmethoxy-phenyl-imido) -perylene, C.I. No. 71140, available from Harmon Colors; a cyan pigment, Monolite Fast Blue GS, the alpha form of metal free phthalocyanine, C.I. No. 74100, available from the Arnold Hoffman Company, and as a yellow pigment, N-2"(1,3-thiazole)- 8,13 dioxodinaphtho (2,1 b; 2',3' d) furan 6 carboxamide. This tri-mix is exposed to a multicolored image and produces a full color image of satisfactory density and good color separation.

EXAMPLE LXVI The pigment suspension consists of a magenta pigment, Calcium Litho Red, the calcium lake of an azo dye, 1-(2'- azo naphthlene l sulfonic acid) 2 hydroxy naphtho, C.I. No. 15630, available from Collway Colors; a cyan pigment, Cyan Blue XR, the alpha form of copper phthalocyanine, available from Collway Colors, and a yellow pigment, N 2"(1",3" thiazole) 8,13 dioxodinaphtho-(2,1-b; 2',3'-d)-furan-6-carboxamide. This tri-mix is exposed to a multicolored image and produces a full color image of good density and color separation.

The novel compositions of the general formula given above are also useful in xerographic imaging systems. For use in such processes, xerographic plates may 'be produced by coating a relatively conductive substrate, e.g. aluminum or paper, with a dispersion of particles of the photosensitive pigment of the above general formula in a resin binder. The pigment-resin layer may also be cast as a self-supporting film. The plate formed may be both with or without an overcoating on the photoconductive layer. As a third alternative to the above noted self-supporting layer and substrate supported layer, the photosensitive pigment-resin photoconductive layer may be used in the formation of multilayer sandwich configurations adjacent a dielectric layer, similar to that shown by Golovin et al., in the publication entitled, A New Electrophotographic Process, Etfected by Means at Combined Electret Layers, Doklady Akad. Nauk SSSR, vol. 129, No. 5, pp. 1008-1011, November-December 1959.

When it is desired to coat the pigmented resin film on a substrate, various supporting materials may be used. Suitable materials for this purpose include aluminum, steel, brass, metalized or tin oxide coated glass, semi-conductor plastics and resins, paper and any other convenient materials. Any suitable dielectric material may be used to overcoat the photoconductive layer. A typical overcoating is bichromated shellac.

Any suitable organic binder or resin may be used in combination with the pigment to prepare the photoconductive layer of this invention. In order to be useful the resin used in the present invention must be more resistive than about 10 and preferably more than 10 ohms 'per centimeter under the conditions of xerographic use. Typical resins include thermoplastics such as polyvinylchloride, polyvinylacetates, polyvinylidenechloride, polystyrene, polybutadiene, polymethacrylates, polyacrylics, polyacrilonitrile, silicone resins, chlorinated rubber, and mixtures and copolymers thereof where applicable; and thermosetting resins such as epoxy resins including halogenated epoxy and phenoxy resins, phenolics, epoxy-phenolic copolymers, epoxy ureaformaldehyde copolymers, epoxy melamine formaldehyde copolymers and mixtures thereof where applicable. Other typical resins are epoxy esters, vinyl epoxy resins, tall-oil modified epoxies, and mixtures thereof where applicable. In addition to the above noted binder materials, any other suitable resin may be used if desired. Also, other binders such as paraffin and mineral waxes may be used if desired.

The pigments may be incorporated in the dissolved or melted binder resin by any suitable means such as strong sheet agitation, preferably with simultaneous grinding. These include ball milling, roller milling, sand milling, ultrasonic agitation, high-speed blending and any desirable combination of these methods. Any suitable range of pigment-resin ratios may be used.

The pigment-resin-solvent slurry (or the pigment-resin melt) may be applied to the conductive substrate by any of the well known painting or coating methods, including spraying, flow coating, knife coating, electro-coating, Mayer bar drawdown, dip coating, reverse foll coating, etc. Spraying in an electric field may be preferred for the smoothest finish and dip coating for convenience in the laboratory. The setting, drying and/or curing steps for these plates are generally similar to those recommended for films of the particular binder used for other painting applications. For example, pigment-epoxy plates may be cured by adding a crosslinking agent and stoving according to approximately the same schedule as other baking enamels made with the same resins and similar pigments for paint applications. A very desirable aspect of these pigments is that they are stable against chemical decomposition at the temperatures normally used for a wide variety of bake-on enamels, and therefore, may be incorporated in very hard glossy photoconductive coatings, similar to automotive or kitchen appliance resin enamels.

The thickness of the photoconductive films may be varied from about 1 to about 100 microns, depending on their required individual purpose. Self-supporting film-s, for example, cannot usually be manufactured in thicknesses thinner than about microns, and they are easiest to handle and use in the to 75 micron range. Coatings, on the other hand, are preferably formed in the 5 to 30 micron range. For certain compositions and purposes it is desirable to provide an overcoating; this should usually not exceed the thickness of the photoconductive coating, and preferably not above one-quarter of the latter. Any suitable overcoating material may be used such as bichromated shellac.

The invention as it pertains to xerographic imaging processes will be further described with reference to the following examples, which describe in detail various preferred embodiments of the present invention. Parts, ratios, and percentages are by weight unless otherwise stated.

Xerographic plates for use as in the following examples are prepared as follows. Mixtures using specific pigments and resin binders are prepared by ball milling the pigment on a solution of a resinous binder and one or more solvents until the pigment is well dispersed. This is done by adding the desired parts of the pigment to the desired parts of resin solution in a suitable mixing vessel. A quantity of one-eighth inch steel balls are added and the vessel is rotated for approximately one-half hour in order to obtain a homogeneous dispersion. The cooling slurry is applied onto an aluminum substrate and a wire drawndown rod and force dried in an oven for about 3 minutes at about 100 C. The coated sheets are dark rested for about 1 hour and then tested.

EXAMPLE LXVII A xerographic plate is prepared by initially mixing about 10 parts Lucite 2042, an ethyl methacrylate polymer available from Du Pont, about 90 parts benzene and about 2 parts N-2(1,3-thiazole)-8,l3-dioxodinaphtho-(2,1-b; 2',3'-d)-furan-6-carboxamide. The mixture is coated onto an aluminum substrate to a thickness of about 8 microns and cured. The plate is charged in the dark by means of a corona discharge means to a negative potential of about 400 volts. The charged plate is contact exposed to a film positive for about 30 seconds by means of a high intensity, long wave, ultraviolet lamp (1680 microwatts/cm. of 3660 All radiation at a distance of 18 inches). The latent electrostatic image is then developed by cascading Xerox 1824 toner over the plate. The image developed on the plate is electrostatically transferred to a receiving sheet and heat fused. The image on the receiving sheet is of excellent quality and corresponds to the contact exposed original. The plate is wiped clean of any residual toner and is reused as in the above manner.

EXAMPLE LXVIII A xerographic plate is prepared by initially mixing about 10 parts Lucite 2042, about 90 parts benzene and about 2 parts N-3(l",2,4"-triazole)-8,l3-dioxodinaphtho-(2,1-b; 2',3'-d)-fura.u-6-carboxamide. The mixture is coated onto an aluminum substrate to a thickness of about 8 microns and cured. The plate is charged negative in the dark by means of a corona discharge to a potential of about 400 volts. The charge plate is contact exposed to a film positive for about 30 seconds using a high intensity, long wave, ultraviolet lamp (1680 microwatts/cm. of 3660 AU. radiation at a distance of 18 inches). The latent electrostatic image is developed by cascading the plate with Xerox 1824 toner. The powder image devel- 7 oped on the plates is electrostatically transferred to a receiving sheet and heat fused. The image on the receiving sheet is of excellent quality and corresponds to the contact exposed original. The plate is wiped clean of any residual toner and is reused as in the above described manner.

EXAMPLE LXIX A xerographic plate is prepared by initially mixing about 10 parts Lucite 2042, about parts benzene and about 2 parts N-2"(1",3"-thiazole)-8,l3-dioxodinaphtho-(2,'1- b; 2,3'-d)-furan-6-carboxamide. The mixture is coated onto an aluminum substrate to a thickness of about 8 microns, and cured. The plate is charged negative in the dark by means of a corona discharge to a potential of about 400 volts. The charged plate is exposed for about 45 seconds to a light and shadow image using a Simmons Omega D3 enlarger equipped with a tungsten light source operating at 2950 K. color temperature. Illumination level incident on the plate is 2.8 foot candles as measured with a Weston Illumination Meter Model No. 756. The latent electrostatic image is developed by cascading Xerox 1824 toner over the plate. The powder image developed on the plate is electrostatically transferred to a receiving sheet and heat fused. The image on the receiving sheet is of good quality and corresponds to the contact exposed original. The plate is wiped clean of any residual toner and is reused as in the above described manner.

The third electrophotographic imaging process in which the above listed novel photosensitive pigments are useful is that referred to as surface deformation imaging. As discussed above, this includes both frost and relief deformation of the surface of a deformable layer in image configuration.

Any suitable imaging method may be used in the surface deformation imaging processes of the present invention.

The following methods are typical:

(1) The photoconductive thermoplastic layer is first substantially uniformly charged and exposed to a light and shadow image to be reproduced. The material is then heated until it deforms to form a frost pattern corresponding to the light and shadow image. The frost image thus formed is subsequently fixed or set by permitting the heat deformable layer to cool below its softening point. The image may be erased by reheating the layer in charge free condition to its softening point.

(2) The thermoplastic layer is selectively charged in imagewise configuration. Subsequently, the thermoplastic material is heated, thereby producing a frost image only in those areas upon which the charge was initially deposited. The material is then cooled to fix the image. The image may be erased by reheating if desired.

(3) In an alternative imaging process, the thermoplastic layer is uniformly charged and exposed to a light and shadow image. The material is then exposed to a solvent vapor, which softens the surface so that it deforms to form a frost pattern corresponding to the light and shadow image. Next, the solvent is removed by evaporation to fix or set the image. This image may be layer erased by resoftening the layer surface, by heat or additional solvent vapor.

(4) In still another alternative, a relief image may be formed by scanning the thermoplastic layer with an electron beam, either while the layer is softened, or just prior to heat or solvent softening. This image may be set by returning the layer to its pre-softened condition.

(5) Any of the methods described in detail in copending applications Ser. Nos. 193,277 now U.S. Patent No. 3,196,011, 232,494 now U.S. Patent 3,244,083 and 388,322 abandoned in favor of application Ser. No. 670,824filed May 8, 1962; Oct. 23, 1962 and Aug. 7, 1964, respectively, may be used in the process of this invention. For example the methods of forming the frost or relief image may vary depending upon the intended use of the resulting product. In certain situations, the heat deformable layer 13 may be pretreated before uniformly charging the surface thereof. In addition, various suitable methods may be used to selectively fix and/or erase the material in imagewise configuration.

Any suitable material may be used as the surface deformable coating over the photoconductive layer or as the binder for the photosensitive pigments in a self-deformable layer. Typical surface deformable thermoplastic polymers are low molecular weight polymers of oligomers. Any suitable polymer may be used in the surface deformation process of this invention; typical polymers are aromatic polymers such as polystyrene, alpha methylstyrene; copolymers made from styrene and other materials such as vinyl toluene, methylstyrene, chloronated styrene, and polymers and copolymers made from petroleum cuts and indene polymers; phenolics such as phenol aldehyde resins, phenol formaldehyde resins and mixtures thereof; vinyl polymers such as polyvinylacetate, polyvinylalcohol, polyvinylbutyral, butylmethyl-acrylate-styrene polymers, butylmethacrylate-alcoholated styrene copolymers, styrene-methacrylate-butadiene terpolymers; organo polysiloxanes such as polydiphenylsiloxane; polyesters such as acrylic esters, bisphenol-A type polyesters; bisphenol-A copolymers; complex hydrocarbon polymers such as hydrogenated polyethylene and other mixtures and other copolymers thereof. If desired, deformation characteristics of the films may be improved by incorporation on the surface thereof thin surface skins as disclosed in copending application Ser. No. 338,323, filed July 8, 1964 now abandoned.

The following examples will further specifically define the surface deformable imaging process of the present invention. Parts and percentages are by weight unless otherwise indicated. The examples below are intended to illustrate various preferred embodiments of surface deformable imaging according to the present invention.

Broadly, the surface deformation image, either relie or frost may be formed either (1) by direct deformation of the thermoplastic binder containing the photosensitive pigment or (2) by overcoating the pigmentbinder layer with a thermoplastic layer which is itself deformable.

EXAMPLE LXX A plate is prepared by initially mixing about parts Lucite 2042, an ethyl methacrylate polymer available from Du Pont, about 90 parts benzene and about 2 parts N-2"(1",3"-thiazole) 8,13 dioxodinaphtho (2,1 b; 2',3-d)-furan-6'carboxamide. The mixture is coated onto an aluminum substrate to a thickness of about 8 microns and cured. The plate overcoated with about a 10 micron layer of Piccoflex 100-A (a polyvinylchloride resin obtained from Pennsylvania Industrial Chemicals Company). The composite plate is then charged negative to about 450 volts in the dark by means of corona discharge. The charged plate is exposed for about seconds by projection using a Simmons Omega D3 enlarger equipped with an F/4.5 lens and a tungsten light source of 2950 K. color temperature. Illumination level at the exposure plane is four foot candles as measured with a Weston Illumination Meter Model No. 756. The latent image on the plate is then developed by placing the plate on a heated platen maintained at about 70 C. As the plate is heated to the softening point of the overcoating, a series of very small wrinkles or folds spontaneously forms in unexposed areas, giving the image a frosted appearance.

EXAMPLE LPQH A plate is prepared by initially mixing about 10 parts of Lucite 2042, about 90 parts benzene and about 2 parts N-3"(1",2",4"-t1iazole)-8,13 dioxodinaphtho (2,1-b; 2',3'-d) -furan-6-carboxamide. The mixture is coated onto an aluminum substrate to a thickness of about 8 microns and cured. The plate is overcoated with about a 10 micron layer of Staybelite Ester No. 10, available from the Hercules Powder Company. The composite plate is charged negative in the dark by means of a corona discharge to a potential of about 400 volts. The charged plate is contact exposed to a film positive for about 30 seconds using a high intensity, long Wave, ultraviolet lamp (1680 microwatts/cm. of 3660 AU. radiation at a distance of 18 inches). The frost image is developed by placing the plate on a heated platen maintained at about C. As the plate is heated to the softening point of the overcoating frost again appears in image configuration.

EXAMPLE LXXII A xerographic plate is prepared by initially mixing about 10 parts Lucite 2042, about parts benzene and about 2 parts N-2"(1", 3"-thiazole)-8,13-dioxodinaphtho- (2,1-b; 2',3'-d)-furan-6-carboxamide. The mixture is coated onto an aluminum substrate to a thickness of about 8 microns and cured. The plate is then overcoated with about a 10 micron layer of Staybelite Ester No. 10. The composite plate is given an electrostatic charge, exposed, and heated to the softening point of the overcoating, as in Example LXXI above. When this threshold point is reached, an excellent frost image appears.

Although specific components and proportions have been described in the above examples relating to electrophoretic, xerographic, and heat deformable imaging systems, other suitable materials, as listed above, may be used with similar results. In addition, other materials may be added to the pigment compositions or to the pigmentresin compositions to synergize, enhance or otherwise modify their properties. The pigment composition and/ or the pigment-resin compositions of this invention may be dye sensitized, if desired, or may be mixed or otherwise combined with other photoconductors, both organic and inorganic.

The novel compositions of this invention are further useful as pigments for paints, varnishes, etc., and for plastic molding and coating compositions. They are useful as pigments in paper making processes when a yellow colored paper is desired. The pigments may also be dispersed in synthetic filament forming materials useful in the production of synthetic textiles. The compositions have further uses in certain insecticides, herbicides, and fungicides.

Other modifications and ramifications of the present invention will occur to those skilled in the art upon a reading of the present disclosure. These are intended to be included within the scope of this invention.

What is claimed is:

1. A composition having the general formula:

wherein:

W, X, Y and Z are each selected from the group consisting of O, N, S, Se, and C, at least one being other than C;

each R is selected from the group consisting of H, CH C H N0 OCH OC H CN, SO NH SO NHC H C1, F, Br, I; and I n is a positive integer from l-3.

2. A composition having the general formula:

\o H W-X ii that l I] wherem:

W, X, Y, and Z are each selected from the group consisting of O, N, S, Se, and C, at least one being other than C.

3. N-3"(1,2",4"-triazole)-8,13-dioxodinaphtho-(2,1-b;

2,3'-d) -furan-6-carboxamide.

4. N 2"(l",3-thiazole)-8,l3-dioxodinaphtho-(2,l-b;

2,3'-d)-furan-6-carboxamide.

5. A coating composition comprising a hardenable carrier having dispersed therein a pigment having the general formula:

l i H l W-X 0/ H II i H C Y 0 N H z 0 wherein:

W, X, Y, and Z are each selected from the group consisting of O, N, S, Se, and C, at least one being other than C;

each R is selected from the group consisting of H, CH C H N0 OCH OC H CN, SO NH SO NHC H Cl, F, Br, I; and

n is a positive integer from 1-3.

6. A coating composition comprising a hardenable carrier having dispersed therein N-3(1,2,4"-triazole)8, 13-dioxodinaphtho-(2,1-b; 2,3-d)furan-6-carboxamide.

7. A coating composition comprising a hardenable carrier having dispersed therein N-2"(1",3"thiazole)-8,13- dioxodinaphtho-(2,l-b; 2',3-d)-furan-6-carboxamide.

8. The method of electrophoretic imaging comprising subjecting a layer of a suspension to an applied electric field between at least two electrodes, at least one of which is partially transparent, and simultaneously exposing said suspension to an image through said partially transparent electrode with activating electromagnetic radiation whereby an image is formed on at least one of said electrodes; said suspension comprising a plurality of finely divided particles of at least one color, atleast one of said particles comprising a photosensitive pigment having the general formula:

wherein:

W, X, Y, and Z are each selected from the group consisting of O, N, S, Se, and C, at least one being other than C;

each R is selected from the group consisting of H, CH C H N0 OCH 0C H CN, SO NH SO NHC H Cl, F, Br, I; and

n is a positive integer from 1-3.

9. The method of electrophoretic lmaging comprising subjecting a layer of a suspension toan applied electric field between at least two electrodes, at least one of which is a blocking electrode, and simultaneously exposing said suspension to an image with activating electromagnetic radiation whereby an image is formed on at least one of said electrodes, said suspension comprising a plurality of finely divided particles of at least one color, at least one of said particles comprising a photosensitive pigment having the general formula:

wherein:

W, X, Y, and Z are each selected from the group consisting of O, N, S, Se, and C, at least one being other than C;

each R is selected from the group consisting of H,

CH3, C2H5, N02, OCH3, OC2H5, CN, SO NHC H Cl, F, Br, I; and

n is a positive integer from 1-3.

10. The method of electrophoretic imaging comprising subjecting a layer of a suspension to an applied electric field between at least two electrodes, at least one of which is partially transparent, and simultaneously exposing said suspension to an image through said partially transparent electrode with a source of activating electromagnetic radiation whereby an image is formed on at least one of said electrodes, said suspension comprising a plurality of finely divided particles of at least one color, at least one of said particles comprising N-2 (1",3"-thiazole)-8,13- dioxodinaphtho-(2,l-b; 2,3'-d)-furan-6-carboxamide.

11. The method of electrophoretic imaging comprising subjecting a layer of a suspension to an applied electric field between at least two electrodes, at least one of which is at least partially transparent, said suspension comprising a plurality of finely divided particles of at least two difierent colors in an insulating carrier liquid, the particles of each color comprising a photosensitive pigment whose principal light absorption bands substantially coincides with its principal photosensitive response, simultaneously exposing said suspension to a light image through said transparent electrode and then separating said electrodes whereby an image is formed on the sunface of at least one of said electrodes; the particles of one color comprising compositions having the general formula:

wherein:

W, X, Y, and Z are each selected from the group consisting of O, N, S, Se, and C, at least one being other than C; each R is selected from the group consisting of H, CH 2 02, OCHB: zHs, 2 2

SO NHC H Cl, F, Br, I; and

n is a positive integer from l-3. 12. The method of electrophoretic imaging comprising subjecting a layer of a suspension to an applied electric wherein:

W, X, Y, and Z are each selected from the group consisting of O, N, S, Se, and C, at least one being other than C;

each R is selected from the group consisting of H, CH c 11 N 0011,, OC H CN, SO NH SO NHC H Cl, F, Br, I; and

n is a positive integer from 1-3.

13. The method of electrophoretic imaging comprising subjecting a layer of a suspension to an applied electric field between at least two electrodes, at least one of which is at least partially transparent, said suspension comprising a plurality of finely divided particles of at least two different colors in an insulating carrier liquid, the particles of each color comprising a photosensitive pigment whose principal light absorption bands substantially coincides With its principal photosensitive response, simultaneously exposing said suspension to a light image through said transparent electrode and then separating said electrodes whereby an image is formed on the surface of at least one of said electrodes; the particles of one color comprising N 3"( l",2",4" triazole) 8,13-dioxodinaphtho- (2,l-b;2',3'-d)-furan-6-carboxamide.

14. A xerographic plate comprising a photoconductive layer comprising a binder material and a composition having the general formula:

y H, 0 all I;

wherein:

W, X, Y, and Z are each selected from the group consisting of O, N, S, Se, and C, at least one being other than C;

each R is selected from the group consisting of H, 3 2 5, 2, OCHa, 2 5 2 2, SO NHC H Cl, F, Br, I; and

n is a positive integer from 1-3.

15. A process for forming a latent xerographic image on a photoconductive layer comprising a photoconductive pigment in an organic binder, which comprises electrostatically charging said layer and exposing said layer to a pattern of activating electromagnetic radiation said photoconductive pigment comprising the composition having the general formula:

I WEX H n t ll (flI-IiF-C /Y 0 \Z wherein:

W, X, Y, and Z are each selected from the group consisting of 0, N, S, Se, and C, at least one being other than C;

each R is selected from the group consisting of H, CH C H N0 OCH OC H CN, SO2NH3, SO NHC H Cl, F, Br, I; and

n is a positive integer from 1-3.

16. A method for forming a latent electrostatic charge pattern on a deformable layer which comprises charging said layer, exposing said layer :to a pattern of activating electromagnetic radiation, dissipating atleast a portion of the charge on said layer to thereby form a latent electrostatic charge pattern corresponding to said pattern of activating electromagnetic radiation; said layer comprising an organic binder and a photoconductive pigment composition having the general formula:

wherein:

W, X, Y, and Z are each selected from the group consisting of 0, N, S, Se, and C, at least one being other than C;

each R is selected from the group consisting of H, CH C H N0 OCH OC H CN, SO NH SO NHC H Cl, F, Br, I; and

n is a positive integer from l-3.

17. A method for forming an image on a surface deformable recording medium, said recording medium comprising photoconductive pigment particles in a thermoplastic binder coated on a supporting substrate, which comprises electrostatically charging said recording medium, exposing said medium to a pattern of light and shadow and maintaining the surface of said medium 'in a sufliciently viscous condition to thereby deform at least a portion of said surface in a configuration corresponding to said pattern of light and shadow, said photoconductive pigment comprising the composition having the general formula:

wherein:

W, X, Y and Z are each selected from the group consisting of O, N, S, Se and C, at least one being other than C;

19 20 each R is selected from the group consisting of H, W, X, Y and Z are each selected from the group con- CH C H N OCHg, 00 1-1 CN, SO NH sisting of O, N, S, Se and C, at least one being other SO NHC H C1, F, Br, I; and than C; n is a positive integer from 1-3. each R is selected from the group consisting of H, 18. A method for forming an image on a surface 5 CH C H N0 OCH OC H CN, SO NH deformable recording medium, said recording medium SO NHC H C1, F, Br, I; and comprising photoconductive pigment particles in an n is a positive integer from 1-3. organic binder coated on a supporting substrate and overcoated with a thermoplastic material which comprises References Cited electrostatically charging said recording medium, ex- UNITED STATES PATENTS posing said medium to a pattern of light and shadow and maintaining the surface of said medium in a sufiiciently 2893998 7/1959 Sarto 2603462 viscous condition to thereby deform at least a portion of 2976287 3/1961 Randall 260'449'6 said surface in a configuration corresponding to said pat- 3147283 9/1964 Frey 260-3462 tern of light and shadow, said photoconductive pigment OTHER REFERENCES comprising the composition having the general formula: Suryanarayana et at Naphthoquinone Series from Proceedings Indian Academy of Science, vol. 37A, January-June 1953, part I, pp. 81-91; part H, pp. 921-98; and

I? part III, pp. 99-103.

NORMAN G. TORCHIN, Primary Examiner.

J. c. COOPER HI, Assistant Examiner. 0/ H u th I 11H: Y US. 01. X.R.

wherein:

Patent NO 3 1 UN I'IED S'IA'IES PATENT OFFICE Dated June 3 Inventor) Lester Weinberger It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

line line line line line Column 3, Column 5, Column 5, Column 7, Column 8,

(SEAL) Attest:

delete "frost" and insert -relief. "dispensed" should read --dispersed-. "suspensions" should read -suspens ion-.

"substractive" "fiter" SIGNED AND SEALED APR? 1970 should read -subtractive. should read --filter-.

MILIAM E. 50mm, h Comissione'r of Patents 

